The present invention relates to a new and improved gripper apparatus on a ring spinning or ring twisting machine for gripping empty and/or wound-on bobbin tubes using pegs arranged on a beam extending along the machine, which pegs can be inserted, by suitably moving the beam, into the cylindrical interior spaces of the bobbin tubes, one peg being provided for each bobbin tube, and the pegs being tapered-off at their front end, which is inserted, in which arrangement the gripped bobbins are held by mutually pressing a bobbin tube and a peg inserted into its interior space against each other.
In textile processing, bobbin tubes or bobbin packages in various operations are gripped automatically to be transported from one location to another. As known e.g. from German Pat. No. 1,282,526 and from Swiss Pat. No. 500,303, particularly on ring spinning or ring twisting machines in many cases a plurality of such bobbin tubes or of bobbin packages, respectively, is to be gripped simultaneously. For this purpose gripper devices, arranged on a beam, are inserted into the cylindric interior spaces of the bobbin tubes or of the bobbin packages, respectively, and by pressing these gripper devices and the bobbin tube inside wall against each other, the bobbin tubes are gripped.
In this type of gripping of the bobbin tubes or the bobbin packages cases occur more or less frequently, in which one of the gripper devices is not inserted correctly into the cylindrical interior space of the bobbin tube. This disadvantage is due, if a plurality of bobbin tubes is to be gripped simultaneously, to inaccurate positioning of one of the bobbin tubes, the probability of such inaccurate positioning increasing with the number of bobbin tubes to be gripped simultaneously. For still achieving correct insertion of the gripper device into a bobbin tube even in case the latter is somewhat inaccurately positioned, it is known that the front end of the gripper device, which is to be inserted into the interior space of the bobbin tubes, is tapered-off conically.
This measure improves the conditions. However, the case can still occur, in which the point of the tapered-off front end of the gripper device, to be inserted into the bobbin tube, collides with the upper rim of the bobbin tube head-on. In this case, if pegs of hard material are used, the bobbin tube, the peg or even the beam for the gripper devices, or the elements guiding and moving the beam respectively, can be damaged; on inflatable, bendable gripper devices cracks can develop, in such manner, that these gripper devices have to be replaced. Due to such cracks furthermore the compressed air required for inflating the gripper devices escapes, which can cause prolonged down time. Such damages thus can be of serious nature.